If you look in /etc/cron.weekly/ you should see a file called fstrim. The file contains the command '/sbin/fstrim --all || true' which should trim all mounted file systems that support it. If you feel a weekly run isn't often enough, you could move the file into the /etc/cron.daily/ directory. (which is what I did).

greerd wrote:
If you look in /etc/cron.weekly/ you should see a file called fstrim. The file contains the command '/sbin/fstrim --all || true' which should trim all mounted file systems that support it. If you feel a weekly run isn't often enough, you could move the file into the /etc/cron.daily/ directory. (which is what I did).

Sytemd, I didn't think of that, I'm not sure if your correct or not. Yes Ubuntu based Mint 18.1, which comes default with /etc/cron.weekly/fstrim.
I would expect that if you open a terminal and enter 'sudo fstrim -v /' and you get output, then the command I mentioned above would work if you put it in a file like so: